Explosive



UNITED STTE ENT OFFICE.

WILLIAM RINTOUL, THOMAS JOSEPH NOLAN, AND OLIVER WARD STEVENSTON, SCOTLAND, ASSIGNORS TO N OBELS EXPLOSIV'ES ITED, OF STEVENSTON, SCOTLAND.

sncxmmn, or COMPANY, 1.1

EXPLOSIVE.

1,392,851 Specification of Letters Patent.

No Drawing. Application filed October 19, 1920. Serial No.

To a]? whom it may concern Be it known that we. WILLIAM RINTOUL, THOMAS Josnrri NoLAN, and OLIVER \VARn STICKLANI), all subjects of the King of Great Britain and Ireland, and all residing at Ardeer Factory, Stevenston, Ayrshire, Scotland, have invented certain new and useful Improvements in Explosives, (for which we have filed an application in Great Britain October 10, 1919.) of which the following is a specification.

This invention relates to the manufacture or hardened granulated fibrous nitrocellulose powders for shot-guns consisting of mixtures of fibrous nitrocellulose, metallic nitrates and moderating ingredients that are granulated and subsequently hardened by treatment with a solvent medium that does not destroy the fibrous appearance of the grains. Examples of this class of explosives are the well known shotgun powders Schultze and E. C.

It does not relate to gelatinized or colloided propellant powders. for example. such as are described in United States Patents Nos. 1, 311,909 and 1,312,463 nor powders for military small arms and cannons.

The present process, apart from dealing only with grains which are not suitable for military propellant purposes differs from these patents by the essential use of a non-' volatile gelatinizer for hardening. without which gelatinizing property and desired hardening effect cannot be obtained, al though to produce the deterrent effect aimed at in the patents numbered as above. does not necessarily require the use of a gelatinizer.

This class of explosive has hitherto been manufactured broadly as follows:Nitrocellulose of various degrees of solubility in a mixture of ether and alcohol, is mixed or incorporated with metallic nitrates with or without starch and other moderating ingredients such as mineral jelly or other well known moderators. The wet mechanical mixture is subdivided by being passed through a sieve and the rough particles so produced formed into grains by revolving in pans. or by shaking on vibrating plates or by other means. The dried grains are too soft for the purposes required, and it is the practice to harden them by moistening with volatile solvents that have a solvent action Patented Oct. 4, 1921. 418,082.

on the nitrocellulose base, thereby on drying.

considerable quantities of these solvents are required for hardening.

It is well known that the method of hardening described above is an expensive operation even when solvent recovery is attempted, and the principal object of the invention is to improve or simplify the production of thls class of explosive by eliminating or reducing the amount of volatile solvent required in the hardening operation.

Now we have discovered that useful hardened granulated fibrous nitrocellulose explosives can be manufactured by the employment of a non-voltatile gelatinizing agent, that is a gelatinizing agent of such a degree of freedom from volatility as to remain substantially in the powder. Thus we have found that by spraying a non-volatile solvent, (which may or may not be miscible with water but is preferably not so miscible) on to the wet grains and then drying out the water say by a stoving operation, only one such operation need be employed instead of two as are required according to common practice.

The invention consists in hardened granu The invention further consists in treating the grains with a solid non-volatile gelatinizer in a finely divided state whereby hardening of the grains is effected.

The invention also consists in treating the grains with an aqueous solution of a nonvolatile gelatinizer preferably in a finely d1- vided state as in a spra whereby hardening of the rains is efi'ecte The invention further consists in treating the grains with a practically concentrated solution of a non-volatile gelatinizer in a volatile organic medium.

In carrying the invention into effect in one form we bring about the hardening of the grain by the combined gelatinizing effect of a reduced quantity of volatile solvent and that of an added non-volatile gelatinizing agent such as (1) Urethanes or esters of substituted carbaminic acid.

(2) Anilids or their homologues.

' (3) Substituted ureas.

(4) Condensation products of glycerol and other olyhydric alcohols with aldehydes.

(5) flomologues of oxanilic ester.

(6) Non-volatile esters of organic acids or mixtures thereof. Examples of some of these gelatinizersapplied to another purpose utilizing the combined gelatinizing effect with nitroglycerin are published in British patent specifications Nos. 4940 and 4941 of 1913. The wet mixture of nitrocellulose, metallic nitrates moderating ingredients and non-volatile gelatinizing agent is granulated in any well known manner and dried. The dried grains are then moistened in any convenient manner with a volatile medium having little or no hardening elfect in the absence of a non-volatile gelatinizer in the explosive, such as, for example, a mixture of alcohol and benzene. We have found that the percentage on the explosive grains of the volatile medium required to harden is substantially -less than that necessary when these non-volatile gelatinizers are not ingredients of the explosive.

In order that the form of our invention may be more fully understood we will describe one example and method of production. A wet mixture of 76 parts of nitrocellulose, 10 parts of barium nitrate, 2 parts of potassium nitrate and 12 parts of a liquid mixture of formanilid and form-o-toluidid are mixed and incorporated under an edge runner. This mixture is rubbed through a sieve 10 meshes to the inch and the sifted material placed in a steam heated revolving pan until the grains are correctly formed and contain about 50% of water. The correct sizes of grains are then sifted out and dried. On to 100 parts by weight of the dried grains 10 parts by weight of a mixture of alcohol and benzene are added by means of a rose and the slightly moistened explosive grains placed in a closed vessel for a few hours so that the volatile medium may uniformly spread throughout the mass. Subsequently the grains are dried and the hardening is effected.

In carrying the invention into effect in another form in which the quantity of volatile solvent is greatly reduced we harden granulated fibrous nitrocellulose explosives by spraying on to the dry or preferably wet grains a concentrated solution of a nonvolatile gelatinizing agent in a volatile organic medium. L

Thus we select the volatile organic medium having regard to the solubility of the particular gelatinizer therein and its suitability for the operation in view. \Ve place the wet or dry grains in a revolving vessel and while the grains are being moved about bring them into contact Withthe finely divided or atomized solution of the gelatinizer by means of any convenient atomizing or spraying appliance. A satisfactory hardening of the grains can be obtained by the use of less than 5 per cent. of the volatile medium on the dry weight of the finished explosive.

Although we prefer to use non-volatile gelatinizing agents that are sufficiently soluble in the selected volatile organic medium at ordinary temepraturcs, nevertheless we do not limit our invention to these substances hut we include such of these agents as become. sufliciently soluble at suitably elevated temperatures. 'By suflieiently soluble we mean that sufficient can be dissolved in the volatile solvent to produce a solution capable of giving the desired hardening effeet. This solubility we consider should be not less than 10%. The temperature should not be higher than'that at which the pow der may be treated with safety but should be high enough to give the necessary solution of the gelatinizer and the desired degree of hardening. We may revolve the wet or dry grains in a heated vessel and spray on to these grains solutions of non-volatile gelatinizing agents at temperatures as high as explosives may be operated upon. The temperature at which the spraying takes place has in some instances a beneficial effeet on the hardening operation. The concentration of the gelatinizer in its solvent, the amount of water present in the grains and the temperature at which the operation takes place are all factors governing the degree of hardening efi'ected in our hardening operation.

The non-volatile gelatinizing agents that are suitable for our urpose are 2- (,1) Nitrohydrocar ns.

Urethanes or esters of carbaminic acl s.

(3) Substituted ureas.

(4) Condensation products of glycerols and other polyhydric alcohols with aldehydes.

(5 Homologues of oxanilic ester.

(6 Non-volatile esters of organic acids.

. (7 ).Anilids or their homologues, or mix.- tures threof.

Each group and each individual member thereof will produce a specific hardening ettect depending on its nature and on the proportion of material present as well as the conditions mentioned above, so by choosing mixtures a wide range in degree of hardening may be secured. Examples of some of these gelatinizers applied to another purpose utilizing their combined gelatinizingeffect with nitroglycerin are published in British patent specifications Nos. 1940 and 4941 of 1913.

The volatile organic medium suitable for our purpose is chosen from individual members of the usual volatile organic solvents such as alcohol, methylated spirit, amylalcohol benzol, petrol, ether, etc., or combinations of the same, the choice depending on the nature of the non-volatile gelatinizer employed. The organic solvent or mixture of solvents should be so chosen that such dissolves the non-volatile gelatinizer and produces a solution with the desired hardening properties.

So that this form of our invention may be more fully understood, we will describe one example and method of roduction. A wet mixture of 7 6 parts of nitrocellulose, 10 parts of barium nitrate, 2 parts of potassium nitrate and 4 parts of mineral jelly, total 92 parts, are mixed and incorporated under an edge-runner. This mixture is rubbed through a sieve 1O meshes to the inch and the sifted material placed in steam heated revolving pans until the grains are correctly formed and contain about 50% of water. The correct sizes of grains are sifted out and dried. The dried grains are placed in a suitable revolving vesseLand while this vessel is being revolved, for every 92 parts dry weight of explosive grain, 8 parts of benzyl formanilid in solution in 5 parts of a mixture of one part of alcohol and two parts of benzene is sprayed onto the grains. These grains are then removed from the vessel and the small amount of volatile medium dried.

out and a well hardened grain results.

In carrying the invention into effect in another form in which the use of a volatile solvent is avoided, we harden wet or dry granulated fibrous nitrocellulose explosives by bringing these granulated explosives into contact with a liquid non-volatile gelatinizer in a finely divided or atomized form, as by a spray. In this method of manufacture we not only avoid the use of volatile solvents, but also eliminate one of the two drying operations at present necessitated in manufacturing hardened granulated fibrous nitrocellulose explosives by the known processes described above.

In this form of our invention, we select either liquid gelatinizers or mixtures of gelatinizers that are liquid at the temperatures it is convenient to work at. A solid gelatinizer may be used by adding a suitable nonvolatile ingredient or ingredients which would have the effect of lowering its melting point without adversely affecting the properties of the powder. The ingredient or ingredients chosen need not necessarily, although they preferably should, possess gelatinizing properties. A suitable example is phenyl urethane to which has been added an equimolecular proportion of tolyl urethane. \Ve place the wet or dry grains in a revolving vessel and while the grains are being movedabout spray on to them the gelatinizing agent by any known convenient atomizing or spraying appliance. A satisfactory hardening of the grains can be obtained by comparatively small amounts of the gelatinizing agent, in some cases by as low as 5% on the dry weight of the finished explosive.

Although we prefer to use non-volatile gelatinizing agents that are liquid at ordinary temperatures, nevertheless we do not limit our invention to these liquids. We may revolve the dry or wet grains in a heated vessel and spray on to these grains liquid non-volatile gelatinizing agents at temperatures as high as explosives may be operated upon. The temperature at which spraying takes place has in some instances a beneficial effect on the hardening operation.

The liquid gelatinizing agents that are suitable for our purpose are quite numerous and the following are given as examples, viz., gelatinizers which are liquids at ordinary temperatures :The liquid nitrohydrocarbons or liquid mixtures of nitrohydrocarbons, ethyl phthalate, phenyl benzyl urethane, formal glycerol, the liquid mixture of formanilid and form-o-toluidid, etc., gelatinizers liquid at temperatures below 50 0., benzyl formanilid, o-tolyl oxamic ester, an equimolecular mixture of methyl phenyl urea and ethyl phenyl urea, etc. Any nonvolatile gelatinizing agent, however, may be used,'the essential feature being spraying a liquid or liquefied non-volatile gelatinizing agent on to wet or dry granulated nitrocellulose mixtures at convenient temperatures for the purpose of hardening these grains without the use of volatile media.

So that this form of our invention may be more fully understood we will describe one example and method of production. A wet mixture of '76 parts of nitrocellulose, 10 parts of barium nitrate, 2 parts of potassium nitrate and 4 parts of Vaseline, total 92 parts, are mixed and incorporated under an edge-runner. This mixture is rubbed through a sieve 10 meshes to the inch and the sifted material placed in a steam heated revolving pan until the grains are correctly formed and contain about 50% of water. The correct sizes of grains are then sifted out and placed in a suitable revolving vessel and while this vessel is being revolved, for every 92 parts dry weight of explosive grain 8 parts by weight of phenyl benzyl urethane is sprayed on to the grains. The wet grains are then removed from the vessel and dried and a well hardened powder is produced.

In carrying the invention into effect in a further form also avoiding the use of a volatile solvent, we harden wet or dry granulated fibrous nitrocellulose explosives by mixing them with one or a mixture of solid gelatinizers in a fine state of division and causing the adhering particles to effect the required hardening, preferably under rise of temperature. In this form of our invention we select solid gelatinizers or mixtures thereof which melt or act at a temperature at which explosives may be operated upon. The solid gelatinizing agent is reduced to a fine state of division and mixed with the wet or dry granulated fibrous explosive, preferably when warm. This mixture is then placed in a suitably heated vessel and left therein until the hardening effect has taken place. The solid gelatinizers suitable for ourpurpose should melt or act below say about 7 0 C. and are quite numerous. The following are quoted as examples, viz., methyl acetanilid, formanilid, an equimolecular mixture of methyl phenyl urea and ethyl phenyl urea, benzyl formanilid, phenyl urethane, tolyl urethane and mixtures of these.

So that this form of our invention may be more fully understood we will describe one example and method of production. The same weight of grains of the correct size containing about 50% water and prepared as in the last example, is, while still warm, mixed with 8 parts of finely divided phenyl urethane, and the mixture is placed in a suitably heated revolving vessel. Heat is applied while the vessel is revolving until the mixture has attained the melting point of the gelatinizer or the temperature at which the gelatinizer acts. Thewet grains are then removed and dried, and a well hardened powder is produced, in an extremely simple and convenient manner.

In carrying this invention into effect in another form also avoiding the use of volatile organic solvents we harden granulated fibrous nitrocellulose explosives without the use of volatile mediums by spraying on to the dry or nearly dry grains an aqueous solution of a non-volatile gelatinizing agent.

We select gelatinizers that are sufficiently soluble in water at the temperatures it is convenient to work at. We place the dry or nearly dry grains in a revolving vessel and while the grains are being moved about bring into contact with them in a finely divided or atomized condition an aqueous solution of the gelatinizing agent by means of any convenient atomizing or spraying appliance.

Although we prefer to use non-volatile gelatinizing agents that are sufiiciently soluble in water at ordinary temperatures, nevertheless we do not limit our invention to these substances, but include such of these agents as become sufficiently soluble at suitably elevated temperatures. We may revolve the dry or nearly dry grains in a heated vessel and spray on to these grains aqueous solutions of non-volatile gelatinizers at temperatures as high as explosives may be operated upon. The temperature at which the spraying takes place has in some instances a beneficial effect on the hardening operation. The concentration of the gelatinizer in the aqueous solution, the amount of moisture present in the grains treated and the temperature at which the operation takes place are all factors of our hardening operation.

The non-volatile gelatinizing agents having the requisite characteristics are quite numerous; the following are given only by way of example, viz., formal glycerol, methyl phenyl urea, ethyl phenyl urea, acetanilid, methyl acentanilid, etc. Any water soluble non-volatile gel atinizing agent,however, may be used that is sufficiently soluble in water to harden at the temperatures that are adopted for the operation.

So that this form of our invention may be more fully understood we will describe one example and method of production. A wet mixture of 76 parts of nitrocellulose, 10 parts of barium nitrate, 2 parts of potassium nitrate, total 88 parts, are mixed and incorporated under an edge-runner. This mixture is rubbed through a sieve 10 meshes to the inch and the sifted material placed in a steam heated revolving pan until the grains are corectly formed and contain about 50% of water. The correct sizes of grains are then sifted out and dried until containing less than 5% of water. The dried or nearly dried grains are placed in a suitable revolving vessel and while this vessel is being revolved, for every 88 parts dry weight of explosive grain, 36 parts of an aqueous solution containing 33% methyl phenyl urea is sprayed on to the grains. The wet grains are then removed from the vessel and dried, and a well hardened product results. If desired. the incorporation of a suitable nonvolatile gelatinizing agent or agents may be made in the manufacture of the grains, the hardening of the grains being effected thereby.

The term spray is employed in the claims to include the application of the gelatinizer or agent in finely subdivided form, whether the agent is liquid or solid at the working temperature: the term liquid non-volatile gelatinizer includes such gelatinizers as are liquid at normal temperatures, or become liquefied at or below the working temperature, or are applied in liquid form in aqueous or non-aqueous solution.

Claims:

1. Hardened granulated fibrous nitrocellulose shot-gun explosives in which the hardening has been effected by the aid of nonvolatile gelatinizing agents. 4

2. Processes for producing hardened granulated fibrous nitrocellulose shot-gun explosives which include the step of hardening the particles of the explosive by the aid of non-volatile gelatinizing agents.

3. A method of manufacturing hardened granular' fibrous nitrocellulose shot-gun explosives Which includes the incorporation of a non-volatile gelatinizing agent in the manufacture of the grains and in bringing about hardening ofthe grains thereby.

4. A method of manufacturing hardened granular fibrous nitrocellulose shot-gun explosives which includes hardening of the dry or nearly dry grains by the combined gelatinizing effect of a volatile solvent and that of an added non-volatile gelatinizing agent and subsequently removing the volatile organic medium.

5. Process according to claim 2 wherein the non-volatile gelatinizing agent is applied in the form of a spray.

6. Process according to claim 5 in which the spray is applied to the wet grains.

7. Process according to claim 5 in which a liquid non-volatile gelatinizer is employed.

In testimony whereof we have signed our names to this specification.

WILLIAM RINTOUL. THOMAS JOSEPH NOLAN. OLIVER \VARD STICKLAND.

Witnesses to the signatures of the above named William Rintoul and ()liver \Vard Stickland:

MATTHEW GEORGE JARDINE, JOHN DONALD MACKENZIE.

Witnesses to the signature of the above named Thomas Joseph Nolan:

EDWARD FEL'roN, ROBERT EVAN Francis. 

